I think the best thing we could do is stop immigration
Think about it you take a third world person who's output of CO2 is 300 lbs per year, now move him to the US where His output of CO2 goes up to about 3,000 pounds per year. It is not a green thing to take eco friendly people and turn them into resource hogs.
Creatures although your idea is nice and all and probably should be done (I am trying to make my company telecommute me (talk about a green move)) Saves 60 miles per day. But lets say we all conserve 25% fuel that only means that we will be back up to current levels in a few years with immigration.

The only green thing to do is force people to not have more than one child 1 per couple. Reduce population thereby conserve resources.